The present invention relates to drinking mugs. In particular, the present invention relates to restricted flow drinking mugs used for measuring and dispensing a precise amount of liquid with each operational cycle.
Restricted flow dispensing mugs are known in the art. Such mugs have been used by children, the elderly and those with medical impairments. With each use, the mug provides the user with a limited amount of fluid that is readily ingested. Some designs also prevent an infant from sucking air while being fed with liquid from the mug. These mugs have the further advantage of limiting the amount of liquid which might be spilled if the mug is overturned.
Juhlin et. al., U.S. Pat. No. 4,921,112, discloses a mug for dispensing a measured quantity of liquid. The mug contains a dosing chamber as well as two spherical valve balls. The valve balls work together to allow fluid to flow into the dosing chamber when the mug is upright or tilted at less then a predetermined angle. If the mug is tilted beyond the predetermined angle a lower valve ball seals the dosing chamber so that no more fluid can enter it, and an upper valve ball dislodges from its sealing engagement with the dosing chamber, thereby allowing fluid to flow out of the chamber to the user.
Hester, U.S. Pat. No. 2,645,388, discloses a dispensing device which maybe used to dispense a measured quantity of liquid from a bottle. The dispenser contains a valve ball operating under the force of gravity to control the flow of liquid from the dispenser. The dispenser also contains a floating valve that shuts off flow from the bottle to the dispenser when the dispenser contains a predetermined amount of liquid. Conry, U.S. Pat. No. 3,321,113, and Brunton, U.S. Pat. No. 4,984,719, disclose controlled volume liquid pouring devices. The devices include a tube containing a valve ball. When the dispenser is tilted at an angle, liquid flows through the device while the valve ball travels the length of tube. Upon reaching the end of the tube the valve ball sealingly engages the outlet of the dispenser and thereby prevents any further liquid from flowing from the dispenser.
While the prior art discloses a variety of restricted flow dispensing mugs, a need remains for a mug which can deliver a precise amount of fluid reliably with each use. Imprecise measurements occur in the prior art as a result of the means by which the measuring chambers are filled with liquid. The filling processes are susceptible to air lock within the chamber or to insufficient filling due to the improper use of the mug. For instance, in Juhlin, the dosing chamber is filled as the user tips the mug in preparation for drinking. If the user tips the mug too quickly, the locking valve ball will close to prevent additional fluid from entering the dosing chamber before the dosing chamber has been filled with fluid. The upper valve ball will then release, allowing an insufficient dosage of fluid to flow to the user.
The prior art further fails to provide a design that efficiently uses the volume of liquid available within the mug. Also, a number of designs employ means for obtaining the fluid (e.g., a nipple) which are socially unacceptable in instances such as the feeding of an elderly patient. Additionally, the designs can be inconvenient for certain users having impairments which limit their physical ability.